The invention relates to an electric lamp, especially energy saving lamp, comprising a discharge tube, a lamp head or socket extending into a rear cover in which an electronic ballast for operating a discharge tube is arranged at least partly, said lamp head having a first and second contact connected to the ballast.
An existing integral energy saving lamp is composed of four parts, namely, a low pressure discharge tube, an electronic ballast, a rear cover and a lamp head. Among them, the lamp head is connected to the lower end of the rear cover. The lamp head is made of metal material, so that it will fit the common lamp socket. However, the screw thread of the lamp head is formed by mold-roll. Therefore, the accuracy of the screw size is not high, the uniformity is poor, and there is 10% below standard in the production (sometimes even up to 30%), so the production cost rises. And more, for the sake of reducing the volume of the energy saving lamp, some of the electronic ballast elements are placed inside the space of the lamp head. However, the lamp head is made of metal conductor and is electrified due to the connection to the power supply, and it is difficult to conform to safety certification demands for the household appliances.
An object of the present invention is to provide an electric lamp, especially an energy saving lamp with a kind of lamp head with high accuracy of screw size, reducing lamp volume, high production yield and lower radio disturbance voltage.
This object is achieved according to the invention by a lamp head comprising a screw plastic part covered at the external surface with a layer of conductive metal film providing the first contact, a contact-point plastic part connected to the end of the screw plastic part, and a metal contact-point fixed at the center of the rear end of the contact-point plastic part providing the second contact.
In an embodiment of the invention the screw plastic part is covered with a layer of conductive metal film on the internal surface.
In another embodiment of the invention the three partsxe2x80x94the lamp head screw plastic part, the contact-point plastic part and the metal contact-point are riveted together.
In a further embodiment of the invention the three parts are made either individually or integrally through plastic-injection of the lamp head screw plastic part and the rear cover of the energy saving lamp as well as the contact-point plastic part.
Compared to the existing energy saving lamp, the advantages of the new one are: due to the plastic injection formation, the accuracy of the size of the screw is high, the uniformity is good. It overcomes the disadvantages of low accuracy of the size of the screw due to metal mold-roll formation, the poor uniformity, and the low production yield. It raises the production yield. Because of the insulation of the plastic part of the lamp head, the space inside the lamp head is isolated from the external surface conductive metal film. It plays the part of electricity insulation. By doing so, if a ballast element is preferably placed inside the lamp head, it will satisfy the safety certification demands. It reduces the volume of the energy saving lamp. Since a coupling capacitance is formed between the element inside the lamp head and screw metal film, the practical fact proves that once the overall arrangement of the element and the wiring is reasonable, not only the harmful coupling is eliminated, but also the coupling capacitance can be used to reduce the conductive disturbance. The lamp head is conformable with E37, E26, E14 and E12 of the IEC Standard.